Ghana received the world’s first delivery of coronavirus vaccines from the United Nations-backed COVAX initiative on Wednesday. 600,000 doses of the AstraZeneca vaccine arrived in the West African country and marks the beginning of the largest vaccine procurement and supply operation in history, according to the World Health Organization and UNICEF.

Ghana is among 92 countries that will receive vaccines for free through the initiative.

COVAX was formed to ensure fair access to vaccines by low- and middle-income countries. But it has been hampered by the severely limited global supply of doses and logistical problems. Although it aims to deliver 2 billion shots this year, it currently has legally binding agreements only for several hundred million shots.

It already missed its own goal of beginning vaccinations in poor countries at the same time immunizations were rolled out in rich ones. The overall campaign thus far has been extremely uneven: 80% of the 210 million doses administered worldwide thus far were given in just 10 countries, WHO Director-General Tedros Adhanom Ghebreyesus said this week.

Even as it celebrated receiving the first doses, Ghana noted the long road ahead.

“The government of Ghana remains resolute at ensuring the welfare of all Ghanaians and is making frantic efforts to acquire adequate vaccines to cover the entire population through bilateral and multilateral agencies,” Ghana’s acting minister of information, Kojo Oppong Nkrumah, said in a statement.